Segment Reporting (Restated) - Segment Wide Reporting Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2013	May 31, 2012
Segment Reporting Information [Line Items]
Sales	$ 121,719	$ 111,283	$ 349,823	$ 322,928
Income (loss) from operations	4,275	3,573	10,825	9,582
Industrial Ingredients [Member]
Segment Reporting Information [Line Items]
Sales	93,184	85,110	267,030	245,927
Income (loss) from operations	565	75	1,500	(161)
Food Ingredients [Member]
Segment Reporting Information [Line Items]
Sales	28,535	26,173	82,793	77,001
Income (loss) from operations	6,206	5,362	17,097	16,563
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Income (loss) from operations	(2,496)	(1,864)	(7,772)	(6,820)
Industrial Starch [Member] | Industrial Ingredients [Member]
Segment Reporting Information [Line Items]
Sales	44,572	43,633	132,610	113,071
Ethanol [Member] | Industrial Ingredients [Member]
Segment Reporting Information [Line Items]
Sales	28,111	23,118	69,710	79,786
By Products [Member] | Industrial Ingredients [Member]
Segment Reporting Information [Line Items]
Sales	$ 20,501	$ 18,359	$ 64,710	$ 53,070